Pre-press proofing is a procedure that is used primarily by the printing industry for creating representative images of printed material. In the printing industry pre-press color proofs are used to check for color balance, control parameters and other important image quality requirements, without the cost and time that is required to actually produce printing plates, set up a printing press, and produce an example of a representative image, which would result in higher costs and a loss of profits that would ultimately be passed on to the customer.
To create a pre-press proof first an original image is separated into individual color separations or digital files. Typically a color scanner is used to create the color separations or digital files and in some instances, more than four color separations or digital files are used.
Although there are several ways used in the printing industry to create a pre-press proof from the color separations or digital files they are generally one of three types. The first method being a color overlay system that employs the representative image on a separate base for each color, which are then overlaid to create a pre-press proof. The second, a single integral sheet process in which the separate colors for the representative image is transferred one at a time by lamination onto a single base. Third, a digital method in which the representative image is produced directly onto a receiver stock, or onto an intermediate sheet then transferred by lamination onto a receiver stock from digital files.
The representative image to be laminated can be created on, but is not limited to, a commercially available Kodak image processing apparatus, depicted in commonly assigned U.S. Pat. No. 5,268,708, which describes an image processing apparatus having half-tone color imaging capabilities. The above-mentioned image processing apparatus is arranged to form a representative image onto a sheet of thermal print media in which colorant from a sheet of colorant donor material is transferred to the thermal print media, by applying a sufficient amount of thermal energy to the colorant donor sheet material to form the representative image. The image processing apparatus is comprised generally of a material supply assembly and a lathe bed scanning subsystem. The scanning subsystem includes: a lathe bed scanning frame, translation drive, translation stage member, printhead, imaging drum, and media exit transports.
The operation of the image processing apparatus comprises of metering a length of the thermal print media in roll form from the material supply assembly. The thermal print media is then measured and cut into sheets of the required length and transported to the imaging drum, registered, wrapped around, and secured onto the imaging drum. Next a length of colorant donor material in roll form is also metered out of the material supply assembly, measured and cut into sheets of the required length. The donor sheets are transported to the imaging drum, wrapped around the imaging drum utilizing a load roller, which is described in detail in commonly assigned U.S. Pat. No. 5,268,708, such that it is superposed in registration with respect to the thermal print media.
After the colorant donor sheet material is secured to the periphery of the imaging drum the scanning subsystem or write engine provides the imaging function. This image function is accomplished by retaining the thermal print media and the colorant donor sheet material on the imaging drum while it is rotated past the printhead. The translation drive traverses the printhead and translation stage member axially along the axis of the imaging drum, in coordinated motion with the rotating imaging drum. These movements combine to produce the representative image on the thermal print media.
Once the representative image has been formed on the thermal print media, the colorant donor sheet material is then removed from the imaging drum. This is accomplished without disturbing the thermal print media that is beneath it. The colorant donor sheet material is then transported out of the image processing apparatus by means of the material exit transport. Additional colorant donor sheet materials featuring other desired colorants are sequentially superimposed with the thermal print media on the imaging drum and then imaged onto the thermal print media as previously mentioned, until the representative image is completed on the thermal print media. The representative image formed is unloaded from the imaging drum and transported by the receiver sheet material exit transport to an exit tray in the exterior of the image processing apparatus.
After a representative image has been formed on the thermal print media it is transferred to a receiver stock such that the pre-press proof is representative of the image that will be printed by the printing press. A Kodak laminator as described in U.S. Pat. No. 5,478,434 can be used to bond or laminate the representative image as a part of a pre-press proofing system. U.S. Pat. No. 5,203,942 describes a Kodak laminator that employs a lamination/de-lamination system as applied to a drum laminator, and U.S. Pat. No. 6,463,981, describes a Kodak laminator that employs endless belts incorporated into the lamination apparatus.
The receiver stock may be sheet-fed press printing stock, specially coated paper stock, or previously laminated stock. In this latter case a sheet of pre-laminate, which has a pre-laminate support layer consisting of a suitable base material, optionally coated with a releasing material, and a thermal print layer, is placed on top of a receiver sheet, which is also called receiver stock in the industry. This construction of multiple layers is a lamination sandwich, which is fed into the laminator. Once the lamination sandwich exits the laminator the pre-laminate support layer is peeled away from the now pre-laminated receiver stock. Any of the laminators referred to above can be used to affect the transfer of the pre-laminate receiving layer to the receiver stock.
U.S. Pat. No. 3,901,755 shows a method of treating plastic material with corona discharge. U.S. Pat. No. 3,901,755, however, uses the corona discharge to oxidize the plastic material with water to form hydrogen bonds. This is also accomplished below the melting point of the material.
The above described lamination method works well for most materials and both laser thermal and inkjet pre-press proofs. There is, however, a need for laminating to a wider variety of plastic materials some of which the thermal print media will not laminate to.